Colorectal Cancer: Which Screening Test Should I Have?

You may want to have a say in this decision, or you may simply want to follow your doctor's recommendation. Either way, this information will help you understand what your choices are so that you can talk to your doctor about them.

4

5

6

Get the facts

Your options

This information is for people who are at average risk for colorectal cancer. Your doctor may recommend getting tested earlier or more often if you have a higher risk.

Key points to remember

All of the screening tests work well to lower your risk of getting and dying from colorectal cancer. No matter what test you choose, regular testing can find signs of cancer early, when the cancer may be easier to treat.

The tests differ in how they are done, how often they are done, and how you prepare for them. Your preferences are important in choosing what test to have. Think about what matters most to you as you look at what each test involves.

No matter which test you choose, it's important that you have the test on the recommended schedule and have any follow-up visits or tests as needed. That gives you the best chance of reducing the risk of dying from colorectal cancer.

Routine testing is recommended for everyone age 50 and older who has an average risk for colorectal cancer. If you are older than 75 or have serious health problems, you and your doctor might decide that it's best for you not to be screened.

Colorectal cancer happens when cells that are not normal grow in your colon or rectum. Most people just call it "colon cancer."

These cancers usually begin as polyps. Polyps are growths attached to the inside of the colon or rectum. Colon polyps are common. Most of them don't turn into cancer. Polyps are found during some screening tests. And polyps found during a colonoscopy usually can be removed at the same time.

With colorectal cancer, symptoms often don't show up until the cancer is advanced. So regular screening—no matter what test you choose—makes it more likely that cancer will be found early, when the cancer may be easier to treat. And colorectal cancer can be prevented if your doctor finds and removes polyps during a colonoscopy.

Most stool tests need to be done once a year. These tests can usually be done in your home.

There are different types of stool tests:

Fecal immunochemical test (FIT). This test checks for signs of blood in the stool. The test kit contains the things that you need for collecting small samples of stool.

Guaiac-based fecal occult blood test (gFOBT). This test also checks for signs of blood in the stool. The test kit contains the things that you need for collecting small samples of stool. With a gFOBT, you will be given instructions about foods to avoid in the days before the test.

Stool DNA (sDNA/Cologuard). This test checks the stool for blood and genetic changes in DNA that could be signs of cancer. The test kit has a container for collecting an entire stool sample. This test is recommended every 3 years.

You can get an at-home stool test from your doctor or your local drugstore, or you can order one online. Your test kit will have instructions about how to do the test, including how to return your stool samples. Some tests provide the results right away. If your test shows a positive result (blood was found), call your doctor as soon as possible. You will need a colonoscopy.

Risks of stool tests

There is no risk from the stool test itself. For this test, you put a sample of stool on a card or you collect a stool sample.

But there are some important things to think about. If your test is positive, you will need to have a colonoscopy. This would be used to see if the stool test result is from colorectal cancer. But blood in the stool is more often caused by something other than cancer. These other causes could include hemorrhoids, ulcers, or taking aspirin. A positive test result could lead you to worry. And you might have a colonoscopy only to find out that you didn't have cancer after all.

Colonoscopy (say "koh-luh-NAW-skuh-pee") is a test that lets your doctor look at the inside of your entire colon. The doctor looks through a lighted tube that can bend around the corners of the colon.

With this test, the doctor can find and remove polyps, which are growths inside the colon that can turn into colorectal cancer.

When used as a screening test for colorectal cancer, this test is usually done every 10 years. If you have a colonoscopy, you won't need to have a yearly stool test. A colonoscopy may be done more often if your risk is higher than average.

Getting ready for a colonoscopy involves a very thorough cleansing of the colon. The colon must be completely empty.

For 1 to 2 days before the test, you will be on a clear liquid diet.

On the night before the test, your doctor may have you take a prescription laxative tablet or drink a large container of laxative solution. This will make you use the bathroom often.

During the test, you may be given medicine to help you relax. Many people don't remember the test afterward because they are so relaxed.

The test usually takes 30 to 45 minutes. But it may take longer if polyps are found and removed.

Risks of colonoscopy

There is a small risk of problems from having a colonoscopy. The scope or a small tool may tear the lining of the colon or cause bleeding. Although these problems are rare, they happen more often with colonoscopy than with sigmoidoscopy. footnote 1

Sigmoidoscopy (say "sig-moy-DAW-skuh-pee") is a test that lets your doctor look at the inside of the lower part of your colon. The doctor looks through a lighted tube that can bend around the corners of the colon.

When used to screen for colorectal cancer, this test is usually done every 5 years. Or you can have the test every 10 years if you also do the FIT stool test every year. Experts say that using both tests on this schedule works better to prevent getting and dying from colorectal cancer than having sigmoidoscopy alone every 5 years. footnote 2

Getting ready for a sigmoidoscopy involves cleaning out the colon.

For 1 to 2 days before the test, you may be on a clear liquid diet.

You will use an enema or laxative (or both) to empty the colon before the test.

This test usually takes 5 to 15 minutes.

Risks of sigmoidoscopy

There is a small risk of problems from having a sigmoidoscopy.

There is a slight chance of piercing the colon (perforation) or causing severe bleeding by damaging the wall of the colon. But this is rare. There is also a very rare chance of a colon infection.

A sigmoidoscopy only looks at the lower part of your colon, which is where most polyps grow. But sometimes polyps grow in the upper part of your colon. Those polyps would not be seen with this test.

If your doctor finds polyps during a sigmoidoscopy, you will need to have a colonoscopy to see if there are more polyps farther up in your colon. And that test also has possible risks.

CT colonography uses pictures taken during a CT scan to look at the colon. A thin tube is inserted into the rectum, and air is pumped through the tube into the colon. The air expands the colon so that it is easier to see on an X-ray.

This test is not done everywhere, so it may not be an option for many people. When used as a screening test, it is usually done every 5 years.

Getting ready for this test involves the same cleansing of the colon that is needed for a regular colonoscopy.

If anything is found during the CT scan, you may need to have more tests, such as a colonoscopy, to make sure that you don't have cancer.

Risks of CT colonography

There is a very small risk that the lining of the colon may be injured or torn when air is pumped into the colon. This may cause bleeding.

CT colonography may find things outside the colon that might never have caused a problem if they had not been found through screening. But this test can't tell whether the problem is harmless. So you may need more tests or treatment. This can cost a lot and cause worry.

You will be exposed to radiation during this test. There is a small chance of getting cancer from having repeated CT colonographies or other CT scans. footnote 3 The chance is higher in people who have many radiation tests.

Some tests may not be available near where you live. Check with your doctor.

Recommendations from the U.S. Preventive Services Task Force

The USPSTF recommends that you have one of the screening tests on its suggested schedule. footnote 2 They don't recommend one test over another. Talk with your doctor to decide which test is right for you.

People ages 50 to 75 should have a screening test starting at age 50.

People ages 76 to 85 can work with their doctors to decide if screening is a good option.

People ages 86 and older are advised that screening for colorectal cancer is usually not helpful.

Recommendations from other groups

The American Cancer Society (ACS), the American Gastroenterological Association (AGA), and the American College of Gastroenterologists (ACG) recommend routine testing for people age 50 and older who have a normal risk for colorectal cancer.

A colonoscopy is the screening test recommended for people at high risk. Your doctor may recommend being tested earlier or more often if you have a higher risk for colorectal cancer. Talk to your doctor about when you should be tested.

Compare your options

Compare

What is usually involved?

What are the benefits?

What are the risks and side effects?

Stool test Stool test

You do the FIT or the gFOBT test every year. Or you do the sDNA test every 3 years.

It's done at home.

You take samples of your stool. You may find out your results right away. Or you may need to mail the sample to a lab or your doctor's office to get the results.

If your test shows a positive result (blood or other signs of cancer are found), you will need to have a colonoscopy.

Screening tests work well to lower your risk of getting and dying from colorectal cancer. For example, with the FIT stool test (over 30 years):

These procedures can find polyps before they turn into cancer. Polyps anywhere in the colon usually can be removed during a colonoscopy. During a sigmoidoscopy, a doctor may be able to remove polyps from the lower colon.

For all procedures

Bleeding problems and a tear in the colon are rare. But they are more common with colonoscopy than with sigmoidoscopy or CT colonography. With colonoscopy, this happens in less than 3 out of 1,000 people. footnote 4footnote 5

These procedures cost more than stool tests.

For sigmoidoscopy

This test only sees the lower part of the colon.

There may be some discomfort during the test.

If polyps are found, you will need a colonoscopy to see if there are more polyps farther up in your colon.

For CT colonography

If polyps are seen during this test, you will need a colonoscopy.

There may be some discomfort during the test.

This test may show problems that are outside the colon. Then other tests or treatment may be needed.

You are exposed to some radiation.

Personal stories about test methods for colorectal cancer

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

No one in my family has ever had colon cancer. I decided on FIT, since I've heard that doing this test yearly is just about as good as having a colonoscopy, but with fewer risks. And I don't have to do the bowel prep.

Patrick, age 56

I've had a fecal occult blood test every year for the past 4 years, and I'm going to continue with this test. My doctor gives me the kit every year and I know what foods to avoid, so it isn't a big deal.

Jose Luis, age 54

When I turned 50, my doctor recommended a yearly FIT with a sigmoidoscopy every 10 years. I'm okay with that. I live in a rural area and I'd have to travel quite a ways to have a colonoscopy. I'd rather have my medical care close to home.

Frank, age 52

I had a colonoscopy. I didn't care for the prep. I had to drink lots of fluid and stay close to the bathroom for the whole time. But the test itself was no big deal. They didn't find any polyps. I like knowing that I don't have to do this again for 10 years.

Stella, age 58

I decided to have a CT colonography. I was glad to find out that I wouldn't need medicine to relax or sedate me, so I would be able to drive myself home after the test. I had planned to go back to work, but my sister—who had the test before—told me to take the afternoon off. I'm glad I did. I didn't have any pain, but I felt gassy and bloated for a couple of hours after the test. It was from the air that was put into my colon for the test.

Nguyen, age 50

I chose the stool DNA test. My medical plan offers several options. I decided on the stool DNA test since I can do this one at home. My doctor said I'd need to do this test every 3 years. Now that I've done it once, I'm fine with that. The test was simple to do, and the directions were easy to follow.

Edna, age 55

What matters most to you?

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

Reasons to have a stool test

Reasons to have a colonoscopy or other procedure

I'm afraid of a test that involves putting anything into my colon.

I'm not too worried about having a test that involves putting something into my colon.

More important

Equally important

More important

I'm okay with doing a test that only checks for signs of blood in my stool.

I want to have a test that is going to see as much as possible.

More important

Equally important

More important

It's important to me to do testing at home, in private.

I don't mind going to a clinic or hospital to have a colonoscopy or other procedure.

More important

Equally important

More important

I don't like the idea of drinking a lot of laxative solution (bowel prep) and spending a long time in the bathroom before a test.

I don't mind having to do the bowel prep before a test.

More important

Equally important

More important

I don't want to miss any work for this test.

I'm not worried about missing work to have this test.

More important

Equally important

More important

I'm willing to do a stool test every year.

I want to get the test over with and not think about it for another 10 years.

More important

Equally important

More important

I'm worried about the cost of having a colonoscopy or other procedure.

I'm not worried about the cost of having a procedure.

More important

Equally important

More important

My other important reasons:

My other important reasons:

More important

Equally important

More important

Where are you leaning now?

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

You may want to have a say in this decision, or you may simply want to follow your doctor's recommendation. Either way, this information will help you understand what your choices are so that you can talk to your doctor about them.

Colorectal Cancer: Which Screening Test Should I Have?

Here's a record of your answers. You can use it to talk with your doctor or loved ones about your decision.

1. Get the Facts

Your options

This information is for people who are at average risk for colorectal cancer. Your doctor may recommend getting tested earlier or more often if you have a higher risk.

Key points to remember

All of the screening tests work well to lower your risk of getting and dying from colorectal cancer. No matter what test you choose, regular testing can find signs of cancer early, when the cancer may be easier to treat.

The tests differ in how they are done, how often they are done, and how you prepare for them. Your preferences are important in choosing what test to have. Think about what matters most to you as you look at what each test involves.

No matter which test you choose, it's important that you have the test on the recommended schedule and have any follow-up visits or tests as needed. That gives you the best chance of reducing the risk of dying from colorectal cancer.

Routine testing is recommended for everyone age 50 and older who has an average risk for colorectal cancer. If you are older than 75 or have serious health problems, you and your doctor might decide that it's best for you not to be screened.

FAQs

What is colorectal cancer?

Colorectal cancer happens when cells that are not normal grow in your colon or rectum . Most people just call it "colon cancer."

These cancers usually begin as polyps. Polyps are growths attached to the inside of the colon or rectum. Colon polyps are common. Most of them don't turn into cancer. Polyps are found during some screening tests. And polyps found during a colonoscopy usually can be removed at the same time.

Why is regular screening important?

With colorectal cancer, symptoms often don't show up until the cancer is advanced. So regular screening—no matter what test you choose—makes it more likely that cancer will be found early, when the cancer may be easier to treat. And colorectal cancer can be prevented if your doctor finds and removes polyps during a colonoscopy.

Why is your family history important?

A family history of colorectal cancer makes you more likely to get it. You may need to be screened at an earlier age—and be tested more often—than other people if:

You have a close relative with colorectal cancer. You are more likely to get colorectal cancer if:

One of your parents, brothers, sisters, or children had it before the age of 60.

Two or more of your parents, brothers, sisters, or children had it at any age.

What are stool tests?

Most stool tests need to be done once a year. These tests can usually be done in your home.

There are different types of stool tests:

Fecal immunochemical test (FIT). This test checks for signs of blood in the stool. The test kit contains the things that you need for collecting small samples of stool.

Guaiac-based fecal occult blood test (gFOBT). This test also checks for signs of blood in the stool. The test kit contains the things that you need for collecting small samples of stool. With a gFOBT, you will be given instructions about foods to avoid in the days before the test.

Stool DNA (sDNA/Cologuard). This test checks the stool for blood and genetic changes in DNA that could be signs of cancer. The test kit has a container for collecting an entire stool sample. This test is recommended every 3 years.

You can get an at-home stool test from your doctor or your local drugstore, or you can order one online. Your test kit will have instructions about how to do the test, including how to return your stool samples. Some tests provide the results right away. If your test shows a positive result (blood was found), call your doctor as soon as possible. You will need a colonoscopy.

Risks of stool tests

There is no risk from the stool test itself. For this test, you put a sample of stool on a card or you collect a stool sample.

But there are some important things to think about. If your test is positive, you will need to have a colonoscopy. This would be used to see if the stool test result is from colorectal cancer. But blood in the stool is more often caused by something other than cancer. These other causes could include hemorrhoids, ulcers, or taking aspirin. A positive test result could lead you to worry. And you might have a colonoscopy only to find out that you didn't have cancer after all.

What is colonoscopy?

Colonoscopy (say "koh-luh-NAW-skuh-pee") is a test that lets your doctor look at the inside of your entire colon . The doctor looks through a lighted tube that can bend around the corners of the colon.

With this test, the doctor can find and remove polyps, which are growths inside the colon that can turn into colorectal cancer.

When used as a screening test for colorectal cancer, this test is usually done every 10 years. If you have a colonoscopy, you won't need to have a yearly stool test. A colonoscopy may be done more often if your risk is higher than average.

Getting ready for a colonoscopy involves a very thorough cleansing of the colon. The colon must be completely empty.

For 1 to 2 days before the test, you will be on a clear liquid diet.

On the night before the test, your doctor may have you take a prescription laxative tablet or drink a large container of laxative solution. This will make you use the bathroom often.

During the test, you may be given medicine to help you relax. Many people don't remember the test afterward because they are so relaxed.

The test usually takes 30 to 45 minutes. But it may take longer if polyps are found and removed.

Risks of colonoscopy

There is a small risk of problems from having a colonoscopy. The scope or a small tool may tear the lining of the colon or cause bleeding. Although these problems are rare, they happen more often with colonoscopy than with sigmoidoscopy. 1

What is sigmoidoscopy?

Sigmoidoscopy (say "sig-moy-DAW-skuh-pee") is a test that lets your doctor look at the inside of the lower part of your colon. The doctor looks through a lighted tube that can bend around the corners of the colon.

When used to screen for colorectal cancer, this test is usually done every 5 years. Or you can have the test every 10 years if you also do the FIT stool test every year. Experts say that using both tests on this schedule works better to prevent getting and dying from colorectal cancer than having sigmoidoscopy alone every 5 years. 2

Getting ready for a sigmoidoscopy involves cleaning out the colon.

For 1 to 2 days before the test, you may be on a clear liquid diet.

You will use an enema or laxative (or both) to empty the colon before the test.

This test usually takes 5 to 15 minutes.

Risks of sigmoidoscopy

There is a small risk of problems from having a sigmoidoscopy.

There is a slight chance of piercing the colon (perforation) or causing severe bleeding by damaging the wall of the colon. But this is rare. There is also a very rare chance of a colon infection.

A sigmoidoscopy only looks at the lower part of your colon, which is where most polyps grow. But sometimes polyps grow in the upper part of your colon. Those polyps would not be seen with this test.

If your doctor finds polyps during a sigmoidoscopy, you will need to have a colonoscopy to see if there are more polyps farther up in your colon. And that test also has possible risks.

What is CT colonography?

CT colonography uses pictures taken during a CT scan to look at the colon. A thin tube is inserted into the rectum, and air is pumped through the tube into the colon. The air expands the colon so that it is easier to see on an X-ray.

This test is not done everywhere, so it may not be an option for many people. When used as a screening test, it is usually done every 5 years.

Getting ready for this test involves the same cleansing of the colon that is needed for a regular colonoscopy.

If anything is found during the CT scan, you may need to have more tests, such as a colonoscopy, to make sure that you don't have cancer.

Risks of CT colonography

There is a very small risk that the lining of the colon may be injured or torn when air is pumped into the colon. This may cause bleeding.

CT colonography may find things outside the colon that might never have caused a problem if they had not been found through screening. But this test can't tell whether the problem is harmless. So you may need more tests or treatment. This can cost a lot and cause worry.

You will be exposed to radiation during this test. There is a small chance of getting cancer from having repeated CT colonographies or other CT scans. 3 The chance is higher in people who have many radiation tests.

What do experts recommend?

Some tests may not be available near where you live. Check with your doctor.

Recommendations from the U.S. Preventive Services Task Force

The USPSTF recommends that you have one of the screening tests on its suggested schedule. 2 They don't recommend one test over another. Talk with your doctor to decide which test is right for you.

People ages 50 to 75 should have a screening test starting at age 50.

People ages 76 to 85 can work with their doctors to decide if screening is a good option.

People ages 86 and older are advised that screening for colorectal cancer is usually not helpful.

Recommendations from other groups

The American Cancer Society (ACS), the American Gastroenterological Association (AGA), and the American College of Gastroenterologists (ACG) recommend routine testing for people age 50 and older who have a normal risk for colorectal cancer.

A colonoscopy is the screening test recommended for people at high risk. Your doctor may recommend being tested earlier or more often if you have a higher risk for colorectal cancer. Talk to your doctor about when you should be tested.

2. Compare your options

Stool test

Colonoscopy or other procedures

What is usually involved?

You do the FIT or the gFOBT test every year. Or you do the sDNA test every 3 years.

It's done at home.

You take samples of your stool. You may find out your results right away. Or you may need to mail the sample to a lab or your doctor's office to get the results.

If your test shows a positive result (blood or other signs of cancer are found), you will need to have a colonoscopy.

You have one of the following procedures:

A colonoscopy every 10 years. It will likely be done more often if you have things that increase your risk for colorectal cancer or if polyps are found.

A sigmoidoscopy every 5 years, or every 10 years with the FIT stool test every year.

A CT colonography every 5 years.

These procedures are done in a doctor's office, clinic, or hospital.

You use laxatives to clean out your bowels.

With colonoscopy, you are given drugs to relax. You may not remember the test at all.

What are the benefits?

Screening tests work well to lower your risk of getting and dying from colorectal cancer. For example, with the FIT stool test (over 30 years):

These procedures can find polyps before they turn into cancer. Polyps anywhere in the colon usually can be removed during a colonoscopy. During a sigmoidoscopy, a doctor may be able to remove polyps from the lower colon.

What are the risks and side effects?

A "positive" result means you will need a colonoscopy to see if there is cancer in your colon. A colonoscopy is a test which also has risks.

For all procedures

Bleeding problems and a tear in the colon are rare. But they are more common with colonoscopy than with sigmoidoscopy or CT colonography. With colonoscopy, this happens in less than 3 out of 1,000 people. 45

These procedures cost more than stool tests.

For sigmoidoscopy

This test only sees the lower part of the colon.

There may be some discomfort during the test.

If polyps are found, you will need a colonoscopy to see if there are more polyps farther up in your colon.

For CT colonography

If polyps are seen during this test, you will need a colonoscopy.

There may be some discomfort during the test.

This test may show problems that are outside the colon. Then other tests or treatment may be needed.

You are exposed to some radiation.

Personal stories

Personal stories about test methods for colorectal cancer

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

"No one in my family has ever had colon cancer. I decided on FIT, since I've heard that doing this test yearly is just about as good as having a colonoscopy, but with fewer risks. And I don't have to do the bowel prep."

— Patrick, age 56

"I've had a fecal occult blood test every year for the past 4 years, and I'm going to continue with this test. My doctor gives me the kit every year and I know what foods to avoid, so it isn't a big deal."

— Jose Luis, age 54

"When I turned 50, my doctor recommended a yearly FIT with a sigmoidoscopy every 10 years. I'm okay with that. I live in a rural area and I'd have to travel quite a ways to have a colonoscopy. I'd rather have my medical care close to home."

— Frank, age 52

"I had a colonoscopy. I didn't care for the prep. I had to drink lots of fluid and stay close to the bathroom for the whole time. But the test itself was no big deal. They didn't find any polyps. I like knowing that I don't have to do this again for 10 years."

— Stella, age 58

"I decided to have a CT colonography. I was glad to find out that I wouldn't need medicine to relax or sedate me, so I would be able to drive myself home after the test. I had planned to go back to work, but my sister—who had the test before—told me to take the afternoon off. I'm glad I did. I didn't have any pain, but I felt gassy and bloated for a couple of hours after the test. It was from the air that was put into my colon for the test."

— Nguyen, age 50

"I chose the stool DNA test. My medical plan offers several options. I decided on the stool DNA test since I can do this one at home. My doctor said I'd need to do this test every 3 years. Now that I've done it once, I'm fine with that. The test was simple to do, and the directions were easy to follow."

— Edna, age 55

3. What matters most to you?

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

Reasons to have a stool test

Reasons to have a colonoscopy or other procedure

I'm afraid of a test that involves putting anything into my colon.

I'm not too worried about having a test that involves putting something into my colon.

More important

Equally important

More important

I'm okay with doing a test that only checks for signs of blood in my stool.

I want to have a test that is going to see as much as possible.

More important

Equally important

More important

It's important to me to do testing at home, in private.

I don't mind going to a clinic or hospital to have a colonoscopy or other procedure.

More important

Equally important

More important

I don't like the idea of drinking a lot of laxative solution (bowel prep) and spending a long time in the bathroom before a test.

I don't mind having to do the bowel prep before a test.

More important

Equally important

More important

I don't want to miss any work for this test.

I'm not worried about missing work to have this test.

More important

Equally important

More important

I'm willing to do a stool test every year.

I want to get the test over with and not think about it for another 10 years.

More important

Equally important

More important

I'm worried about the cost of having a colonoscopy or other procedure.

I'm not worried about the cost of having a procedure.

More important

Equally important

More important

My other important reasons:

My other important reasons:

More important

Equally important

More important

4. Where are you leaning now?

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

Note: The "printer friendly" document will not contain all the information available in the online document some Information (e.g. cross-references to other topics, definitions or medical illustrations) is only available in the online version.

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